This is none on 'ordinary' days, or one of

april_fools_day christmas koningsdag santiklaas

succeeds only within 12 hours either side of April 1

April fools day is a traditional holiday celebrated by playing hoaxes and practical jokes. A common form of this is to substitute nonsensical information where useful info is normally displayed.

Koningsdag is 'Kings day' in the Netherlands Santiklaas is St. Nicholas' feast